In the last years the Internet has seen a rapid growth so that the Internet has become one of the single most important tools for communication. Along with the growth of the Internet the need for quick and ready access to the Internet from any location has increased. As a result access bandwidth demand has been growing at such a pace that the wired infrastructure can not keep up with. The upgrading of the wired infrastructure to provide high-speed and remote Internet access is costly complicated and time consuming, resulting in a bottleneck at the Internet access point the so-called last mile of Internet infrastructure.
Wireless broadband networks make high performance Internet access possible where wired broadband infrastructure is impractical. However, such a wireless broadband network will only be a success especially for residential and small business markets if the infrastructure is provided at a low-cost, is robust to changing environments and easy to deploy and scalable with market demand.
High-performance wireless connections require clear line-of-sight between links. In many environments or surroundings buildings, trees, hills and the topography make line-of-sight difficult.
New wireless networks with wireless routers as network nodes on a mesh network basis emulate the topology and protocols of the Internet but are optimised for wireless high-speed data transmission. As an example of such a wireless broadband solution a wireless routing network has been developed. The key components of such a wireless routing network are a routed mesh network architecture, wireless routers, a wireless operating system and the deployment and management of the network.
Routed mesh networks mirror the structure of the wired Internet. Each radio transceiver at a node in the wireless network becomes part of the infrastructure and can route data through the wireless mesh network to its destination just as in the wired Internet. The advantage of such a routed mesh networks is that line-of-sight problems can be reduced in comparison to a client/base station architecture because each node only needs line-of-sight to one other node in the network and not all the way to the ultimate destination of the data traffic, e.g. the point-of-presence (POP). With such an infrastructure the reach and coverage of the wireless network is extended with a minimal amount of wireless network infrastructure and interconnection costs. The data traffic can be routed around obstructions rather than needing to deploy additional base stations for line-of-sight in densely populated diverse geographical locations. The more wireless routers are added to the network, the more robust and far-reaching the network becomes. In the above mentioned wireless routing network, wireless router with omni-directional antennas are used as a network node. Each wireless router can communicate with other nodes, i.e. other wireless routers in any direction. The omni-directional antennas offer a 360-degree range and do not require precise pointing or steering. Therefore additional wireless routers can be added in an ad hoc and incremental fashion.
The wireless routers substantially comprise three components, namely a full TCP/IP (Transmission Control Protocol/Internet Protocol) protocol suite support, a wireless operating system that optimises the wireless network performance and robustness, and a high-performance digital RF modem. A specialized wireless networking software in combination with the high-performance RF modem optimise the network performance while insuring full IP support and robust and steamless IP routing.
Routed wireless mesh networks deploy specialized protocols, that operate efficiently in a multihop wireless network environment. From the media access control (MAC) layer through to the routing layer new protocols must be used that are specifically designed to deal with their unique attributes. The protocol suite extends the traditional TCP/IP stack to provide efficient and robust IP-based networking in multihop wireless mesh networks. These protocols consist of four parts, namely channel access protocols, reliable link and neighbour management protocols wireless multihop routing and multicast protocols and standard Internet protocols.
In the channel access, protocols are used to efficiently schedule transmissions to avoid collisions and efficiently reuse the available spectrum. Reliable link and neighbour management protocols ensure reliable transmissions on a hop-by-hop basis, and manage the automatic adaptation to changes in the network topology by monitoring the status of neighbour links. The role of the reliable link and neighbour management protocols is to perform network synchronisation and to manage the links to each neighbour node. Wireless multihop routing and multicast protocols maintain performance-optimised routing tables and enable an efficient multicast capability. The standard Internet protocols and tools for seamless integration with the wired Internet. The protocols and tools are for example TCP/IP, UDP (User Datagram Protocol), SNMP (Simple Network Management Protocol), RIP, ICMP (Internet Control Message Protocol), TFTP, ARP, IGMP, Proxy-ARP, DHCP relay (Dynamic Host Configuration Protocol), DHCP server, NAT (Network Address Translation).
Wireless mesh networks based on a multipoint-to-multipoint architecture make an ad hoc integration of new nodes, i.e. wireless routers, easier, since the actual demand and traffic flow in such a wireless network environment makes it much easier to adjust the coverage and bandwidth needs than design a network ahead of time. Adaptive routed mesh network make obstructions to the line-of-sight acquirements by growing trees of temporary obstructions less problematic, since the data traffic is automatically re-routed through as a link becomes unavailable. The nodes, i.e. wireless routers, in such an wireless routing network environment can adapt to changes in the link availability and the quality in real-time without requiring intervention by a network administrator.
A network operating system continuously monitors the status and quality of the links and makes real-time routing decisions based on the current network status. New nodes can be authenticated and assimilated into the network topology without manual reconfigurations.
Before a new node, i.e. a wireless router, can be added to the wireless network it is an essential question, whether, such a new node at a specific position lies within the coverage of the wireless network.
So far, a static map with predefined coverage areas has been used for the above determination of a network coverage, or alternatively a side survey was carried out.